Multiple pregnancies and assisted reproduction: the pros and cons

In the last decade, the number of women who have given birth to twins or even triplets has increased. Furthermore, mutliple pregnancies are often related to assisted reproduction treatments. This has led fertility specialists to establish a series of guidelines to prevent this, since multiple pregnancies entail more risks than singleton pregnancies.

Being pregnant with more than one embryo can lead to severe complications for both the health of the mother and the babies. Despite this there are patients who desire a mutliple pregnancy. As such is it necessary to understand and carefully evaluate the pros and cons of this type of pregnancy.

Multiple pregnancy and assisted reproduction.

The reason why assisted reproduction may increase the rate of multiple pregnancy is different depending on the assisted reproductive technique used.

Artificial insemination(AI)

In artificial insemination (AI), a gentle ovarian stimulation is usually performed on the patient. The objective is the development of a single follicle or two (at most), so that finally fertilizes a single egg.

It may be the case that both eggs are fertilized and both implant. Therefore, AI can increase the likelihood of multiple pregnancy.

Multiple pregnancy following artificial insemination (AI)

However, if more follicules mature than are recommended, the AI cycle should be canceled due to the high risk of multiple gestation.

In vitro fertilization (IVF)

Unlike AI, the ovarian stimulation the patient undergoes with in vitro fertilization (IVF) aims to develop and mature several ovarian follicles at once. In this way, it will be possible to obtain a greater number of eggs to fertilize in the laboratory and thus increase the chances of having viable embryos that can lead to pregnancy.

Subsequently, the IVF treatment requires the transfer of the selected embryo or embryos into the patient's uterus. Obviously, the transfer of more than one embryo in the same IVF cycle increases the probability of having a multiple pregnancy increases.

Mutliple pregnancy following IVF

For this reason, the current trend among specialists is the transfer of a single embryo. A larger number of embryos would be transferred only in cases of poor prognosis, in order to try to increase the chances of gestation.

Nevertheless, it is important to clarify that the transfer of several embryos does not necessarily mean that a multiple pregnancy will occur. It is possible that some of the embryos transferred will not implant in the uterus or even that none of the embryos will implant and, therefore, there will be no pregnancy.

Fraternal vs. identical twins in ART

Multiple pregnancies achieved following assisted conception result in fraternal twins and not in identical twins, since they are the result of two eggs that have been fertilized using two different sperms. In other wrods the siblings will be alike as for brothers and sisters from separate pregnancies, and can be of different genders.

Twin pregnancy after assisted reproduction treatment

However, there is also the possibility of a twin pregnancy occurring naturally due to the embryo splitting in two after AI or embryo transfer. In this case, identical twins would result.

I want to have twins!

Nowadays, reproductive endocrinologists and infertility specialists insist on the importance of elective single embryo transfers (eSETs) to prevent a multiple pregnancy. However, many patients disagree with this.

Most intended parents do not want to stack everything on a single embryo. In fact, they prefer to have fraternal twins from a single cycle in order not to go through another cycle in the future to have more children. But, it should be remebered that embryo transfer is a simple procedure and does not usually have any negative side effects for the patient.

Fertility treatments are hard to cope with emotionally. Several regular visits to the clinic, along with the expensive cost of fertility treatments per cycle, make them inaccessible for many families.

For these reasons, a mutliple pregnancy following an assisted reproductive treatment can present certain advantages as well as disadvantaged, which we are going to look at here below.

The pros of multiple pregnancies

As we have explained above, the main advantage of a multiple pregnancy following ART is that the couple does not need to start a cycle anew. With the birth of two babies at the same time, they fulfil their dream of becoming parents and don't usually look for a further pregnancy.

Advantages of a multiple pregnancy in ART

Another advantage is that, when pregnant with twins, the intended mother goes through pregnancy and childbirth only once, experiences that not all women want to repeat.

Finally, we should mention the special bond that develops between twins. They grow up together, learning to share everything with each other, and become excellent playmates.

The cons of multiple pregnancies

In addition to the complications of raising children, such as increased workload, sleepless nights, money outlay, etc., the disadvantages of multiple pregnancies are due to the risks that this type of pregnancy entails for the mother and the babies. Among these risks are:

Preeclampsia

a type of high blood pressure that occurs during pregnancy. It causes kidney problems, causing the loss of proteins through urine.

Gestational diabetes

a version of diabetes that appears for the first time when the woman gets pregnant. It typically appears after the first trimester.

Miscarriage or vanishing twin syndrome

although most twin pregnancies develop without problems, the risk of miscarriage is higher than in singleton pregnancies.

dt>Intrauterine growth restriction

the fetus is unable to grow as needed due to a deficiency of nutrients and/or oxygen.

Disadvantages of multiple pregnancy in ART

Preterm birth

when delivery occurs before week 37 of pregnancy.

C-section birth

a surgical incision is performed on the abdomen and the uterus to deliver the babies.

Low birth weight

diagnosed when the weight of the baby is less than 5lb 8oz.

Congenital abnormalities

alterations that are present at birth

Perinatal mortaility

the risk is increased in multiple pregnancies, related to prematurity

Due to these many risks, there are occasions when AR patients are advised to undergo multifetal pregnancy reduction if various embryos have implanted, after proper assessment and counseling.

FAQs from users

Is a preterm birth more likely with twins?

By Manuel Aparicio Caballero M.D., M.Sc. (gynecologist).

According to the World Health Organization (WHO), a preterm birth occurs when the child is born before the week 37 of pregnancy. Some of the most common causes of preterm birth are:

• Overdistention of the uterus: loss of tone in the uterine musculature that prevents this organ to recover its normal size.
• Infection or uterine inflammation: certain bacteria can damage fetal membranes by causing its rupture and triggering a preterm birth. An infection that affects the uterus directly may lead to preterm birth as well.
• Decidual bleeding: a type of vaginal bleeding that may occur while a woman is pregnant.

There exist many risk factors that can lead to premature birth, including obesity, high blood pressure, etc. A multiple pregnancy is one of these factors.

How can multiple pregnancy from assisted reproductive technology be prevented?

By Manuel Fernández M.D., Ph.D. (gynecologist).

There are lots of actions to be taken, most of them being implemented with increasing success.

As for in vitro fertilisation, a three-embryo transfer should be avoided: cases with a good prognosis should bet on a single embryo transfer instead. This requires a process of raising awareness not only by the couple undergoing the treatment but also by the professional team.

The “success” of an assisted reproductive treatment does not consist only on achieving pregnancy. More and more, we need to be aware that the ultimate aim should be having a healthy baby, that is to say, that the child is not born too early.

Even though changing this mindset may be difficult, we insist on the need of it to prevent multiple births.

Is it possible to achieve a multiple pregnancy with Omifin?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Omifin is a medication used by women with polycystic ovary syndrome in order to ovulate. In addition, Omifin also causes follicular maturation in the ovary. Therefore, ultrasound monitoring and administration of the appropriate dose is necessary to avoid multiple gestation.

I want to have twins. Can I make this decision in my IVF cycle?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Yes, it is possible for a woman or couple to decide to transfer two or more embryos instead of just one. However, you should follow strictly the recommendations of specialists and prevent the risks a multiple pregnancy entails. Moreover, not all embryos transferred are always able to attach to the uterus.

Can you get pregnant with twins after using donor eggs?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Yes, although it depends on the number of embryos transferred. Moreover, the pregnancy success rates with donor eggs are higher than with own eggs, given that donor eggs have an excellent quality.

Recommended reading

To get more information about how the decision of how many embryos to transfer in an IVF cycle is made, click here: How Many Embryos Should You Transfer for IVF?

A multiple pregnancy entails several risks, especially in women of an advanced maternal age. If you would like to read more about this then please visit the following article: Risks associated with multiple pregnancy.